The law relating to the variation of trusts pursuant to s 64A of the Trustee Act 1956 is helpfully re-stated in Clarkson v Bradey at  to  as follows:
“ Section 64A places the Court in the shoes of any minor, unascertained, unborn or unknown persons who are or may become beneficiaries of the trust in its current form. It empowers the Court to consent on their behalf to an arrangement varying or revoking the relevant trust. The Court may not do so if the arrangement is to the detriment of any such person. In assessing that the Court:
… may have regard to all benefits which may accrue to him directly or indirectly in consequence of the arrangement, including the welfare and honour of the family to which he belongs.
 As Tipping J put it in Re Greenwood:
The purpose of s 64A is in my view to put the court into the shoes of a beneficiary who is, by reason of infancy or other incapacity, incapable of assenting to the variation, revocation or enlargement of powers proposed. Similarly the Court is put in the shoes of unborn and unknown persons. The Court, as one part of its consideration of the application, should ask itself whether, if the person on whose behalf it is acting had been alive and of full capacity and properly advised, that person would have been likely to have approved the arrangement on his or her own behalf and with or without conditions or amendment to the scheme.
 The principles expounded in that decision and in others such as Re Byrne and Ewington v Schultz have been collected usefully by French J in McKnight v Craig in these terms5:
The following principles may be distilled from the authorities …
(i) The power to approve a variation is discretionary.
(ii) The court may consider any proposal which varies or revokes any, or all, of the trusts or a proposal which enlarges the powers of the trustees in managing or administering the property subject to the trust.
(iii) The discretion is exercised in the interests of the person on whose behalf the court is asked to approve the variation and from their point of view. The court should therefore ask itself whether the person would have given approval if that person were alive, of full capacity and properly advised.
(iv) The court can approve a scheme which conflicts with the intentions of the settlor but should not do so light.
(v) The court considers the trust provisions afresh if circumstances have arisen which were not foreseen or may not have been foreseeable at the time the trust was established.
(vi) The court cannot approve an arrangement to the detriment of any person on whose behalf the court is giving consent.
(vii) But the court is to take a wide approach to benefits and detriments in arrangements and must consider the arrangements as a whole in a practical and business-like way. Indirect and intangible benefits and detriments are relevant including the welfare and honour of the family.
(viii) Difficulties may be met by amendments to the proposal or covenants by persons benefitting to make good losses to the disadvantage of other beneficiaries.
(ix) An order approving a proposed variation may be conditional.”
McKnight v Craig involved a successful application for the approval the resettlement of two existing mirror family trusts into a single trust. This enabled the two original settlors to become discretionary beneficiaries of the whole corpus of the assets held by the two trusts, rather than half each.
Clarkson v Bradey usefully highlights matters that need to be taken into consideration when seeking the Court’s assistance. In that case the effect of the proposed variations was:
(a) To expand the beneficiaries of the Clarkson Trusts to include trusts the beneficiaries of which are also beneficiaries of the Clarkson Trusts.
(b) To make it possible for the Clarkson Trusts to distribute income to another family trust that was in financial difficulty.
(c) Tax benefits.
The court allowed the variation as the proposed arrangement was “not detrimental to the relevant interests when compared to their status quo ante.”